SED(1) SED(1)
NAME
sed - stream editor
SYNOPSIS
sed [ -n ] script [ file ... ]
sed [ -e script ] [ -f sfile ] [ file ... ]
DESCRIPTION
Sed copies the named files (standard input default) to the
standard output, edited according to a command script.
Script options accumulate.
-e script
Script is given literally in command line.
-f sfile
Script is given in file sfile.
-n Suppress the default output.
A script consists of editing commands, usually one per line.
If a command ends with `;', `{', or `}', the next command
begins immediately thereafter. Empty commands are ignored.
Commands have the form
[address [, address] ] function [argument ...] [;]
In normal operation sed cyclically copies a line of input
into a pattern space (unless there is something left after a
`D' command), applies in sequence all commands whose
addresses select that pattern space, and at the end of the
script copies the pattern space to the standard output
(except under -n) and deletes the pattern space.
An address is either a decimal number that counts input
lines cumulatively across files, a `$' that addresses the
last line of input, or a context address,
/regular-expression/, in the style of ed(1), with the added
convention that `\n' matches a newline embedded in the pat-
tern space.
A command line with no addresses selects every pattern
space.
A command line with one address selects each pattern space
that matches the address. (Address `0' is never matched.)
A command line with two addresses selects the inclusive
range from the first pattern space that matches the first
SED(1) SED(1)
address through the next pattern space that matches the sec-
ond. (If the second address is a number less than or equal
to the line number first selected, only one line is
selected.) Thereafter the process is repeated, looking
again for the first address.
Editing commands can be applied to non-selected pattern
spaces by use of the negation function `!' (below).
In the following list of functions the maximum number of
permissible addresses for each function is indicated in
parentheses.
A text argument consists of one or more lines, all but the
last of which end with `\' to hide the newline. Backslashes
in text are treated like backslashes in the replacement
string of an `s' command, and may be used to protect initial
blanks and tabs against the stripping that is done on every
script line.
An rfile or wfile argument must terminate the command line
and must be preceded by exactly one blank. Each wfile is
created before processing begins. There can be at most 120
distinct wfile arguments.
(1)a\
text Append. Place text on the output before reading the
next input line.
(2)b label
Branch to the : command bearing the label. If label is
empty, branch to the end of the script.
(2)c\
text Change. Delete the pattern space. With 0 or 1 address
or at the end of a 2-address range, place text on the
output. Start the next cycle.
(2)d Delete the pattern space. Start the next cycle.
(2)D Delete the initial segment of the pattern space through
the first newline. Start the next cycle.
(2)g Replace the contents of the pattern space by the con-
tents of the hold space.
(2)G Append the contents of the hold space to the pattern
space.
(2)h Replace the contents of the hold space by the contents
of the pattern space.
SED(1) SED(1)
(2)H Append the contents of the pattern space to the hold
space.
(1)i\
text Insert. Place text on the standard output.
(2)l Literal. Place an unambiguous image of the pattern
space on the standard output, using C escape sequences.
Break long lines, indicating the breakpoint by a single
backslash. Append \n if pattern space ends with space
or newline.
(2)n Copy the pattern space to the standard output. Replace
the pattern space with the next line of input.
(2)N Append the next line of input to the pattern space with
an embedded newline. (The current line number
changes.)
(2)p Print. Copy the pattern space to the standard output.
(2)P Copy the initial segment of the pattern space through
the first newline to the standard output.
(1)q Quit. Branch to the end of the script. Do not start a
new cycle.
(2)r rfile
Read the contents of rfile. Place them on the output
before reading the next input line.
(2)s/regular-expression/replacement/flags
Substitute the replacement string for instances of the
regular-expression in the pattern space. Any character
may be used instead of `/'. For a fuller description
see ed(1); although unlike ed , the trailing / must be
supplied. Flags is zero or more of
g Global. Substitute for all non-overlapping
instances of the regular expression rather than
just the first one.
p Print the pattern space if a replacement was made.
w wfile
Write. Append the pattern space to wfile if a
replacement was made.
(2)t label
Test. Branch to the `:' command bearing the label if
any substitutions have been made since the most recent
reading of an input line or execution of a `t'. If
SED(1) SED(1)
label is empty, branch to the end of the script.
(2)w wfile
Write. Append the pattern space to wfile.
(2)x Exchange the contents of the pattern and hold spaces.
(2)y/string1/string2/
Transform. Replace all occurrences of characters in
string1 with the corresponding character in string2.
The lengths of string1 and string2 must be equal.
(2)! function
Don't. Apply the function (or group, if function is
`{') only to lines not selected by the address(es).
(0)# Comment. Ignore the rest of the line.
(0): label
This command does nothing; it bears a label for b and t
commands to branch to.
(1)= Place the current line number on the standard output as
a line.
(2){ Execute the following commands through a matching `}'
only when the pattern space is selected.
(0) An empty command is ignored.
EXAMPLES
sed 10q file
Print the first 10 lines of the file.
sed '/^$/d'
Delete empty lines from standard input.
sed 's/UNIX/& system/g'
Replace every instance of `UNIX' by `UNIX system'.
sed 's/ *$// drop trailing blanks
/^$/d drop empty lines
s/ */\ replace blanks by newlines
/g
/^$/d' chapter*
Print the files chapter1, chapter2, etc. one word to a
line.
nroff -ms manuscript | sed '
${
/^$/p if last line of file is empty, print it
}
SED(1) SED(1)
//N if current line is empty, append next line
/^\n$/D' if two lines are empty, delete the first
Delete all but one of each group of empty lines from a
formatted manuscript.
ls /usr/* | sed '
/^$/d delete empty lines
/^[/].*:$/{ look for lines like /usr/lem:
s/:$/\// replace : by /
h hold directory name
d don't print; get next line
}
G append held directory name
s/\(.*\)\n\(.*\)/\2\1/' exchange file and directory
List all files in user directories, as ls -d /usr/*/*
would do if it didn't cause argument list overflow.
SEE ALSO
ed(1), gre(1), awk(1), lex(1), cut(1), split(1), sam(9.1)
L. E. McMahon, `SED - A Non-interactive Text Editor', this
manual, Volume 2.
BUGS
If input is from a pipe, buffering may consume characters
beyond a line on which a `q' command is executed.